Field of the Invention
The present invention relates to an antenna device and a manufacturing method thereof and, more particularly to an antenna device suitable for NFC (Near Field Communication) system and a manufacturing method thereof.
Description of Related Art
In recent years, a mobile electronic apparatus such as a smartphone is provided with an RFID (Radio Frequency Identification, i.e., individual identification by radio waves) system and further provided with, as a communication means of the RFID, an antenna device for performing near field communication with a reader/writer. For example, a conventional antenna device described in Japanese Patent Application Laid-Open No. 2008-117944 has a base substrate made of a plastic film, an antenna coil formed on the base substrate, a metallic shield plate provided at a position overlapping the antenna coil in a planar view, and a magnetic core member provided between the antenna coil and metallic shield plate. Such an antenna device is accommodated in a casing of a mobile electronic apparatus such as a smartphone and is disposed on a surface of a battery pack or a surface of a printed circuit board.
However, recently, a reduction in thickness of the mobile electronic apparatus is highly required, and a further thickness reduction is required for the antenna device itself. Further, in a case where the antenna device is mounted on a surface of a heating element such as a battery pack, the base substrate may block heat radiation from the battery pack because the antenna coil is supported on the base substrate. Further, because the base substrate is made of a dielectric material, an inter-line capacitance of the antenna coil becomes large due to an intervention of the dielectric material between lines of the antenna coil, making it difficult to achieve frequency matching.